Office and other in-door work environments require artificial lighting to supply interior illumination. Interior illumination falls into three main classes: (1) direct lighting, (2) indirect lighting, and (3) a combination referred to as direct/indirect lighting. “Direct” is illumination directed below the horizontal plane. “Indirect” is illumination directed above the horizontal plane. “Direct/indirect” is illumination directed above and below a horizontal plane.
A common, prevalent, older direct lighting system in current use is a recessed lensed troffer or parabolic unit. Representative recessed troffer lighting systems are disclosed by U.S. Pat. No. 4,504,891 to Mazis and U.S. Pat. No. 4,146,287 to Jonsson.
While these direct lighting systems provide acceptable lighting in many work environments, the lighting provided in business environments utilizing computer systems is not wholly satisfactory. Employees working with computer screens often complain of glare on their screens from improper direct lighting levels and locations. Another complaint arising from direct lighting is a cave-like feeling for employees and customers created by dark upper walls and ceiling areas. Another complaint about direct lighting is improper contrast ratios between highly reflective surfaces (e.g. paper) that are bright and dark computer screens, walls, or ceilings. Shadows created by objects blocking direct light illumination are also a common problem.
Building owners also often complain of high-energy consumption, high maintenance costs, and difficulty in properly positioning direct lighting systems to accommodate the individual needs of employees. For example, an industry standard for 2-foot by 4-foot recessed parabolic systems is one unit used to illuminate 80 square feet of floor space, which requires 110 watts of electricity. A 20,000 square foot facility with 160 employees would use 250 recessed parabolic units requiring 27,500 watts of electricity.
In recent years, linear indirect or direct/indirect systems became an alternative lighting option to direct lighting systems. These linear indirect systems used pre-wired sections of lighting devices shipped to the building site and assembled section-by-section to form continuous rows of light fixtures suspended from the ceiling into the workspace below. These suspended light systems directed light to the bottom of the ceiling surface to reflect light to the area below. An example of a linear indirect light system is disclosed by U.S. Pat. No. 6,305,816 B1 to Corcarran et al. The reflected light from this type of linear indirect system decreased employee complaints associated with direct lighting systems (e.g. less glare on computer screens), and studies from various universities and private corporations showed these linear indirect lighting systems increased productivity of employees and lowered energy consumption by allowing reduced lighting levels to adequately illuminate an office work environment.
Over time, the linear indirect light systems became less expensive to manufacture, and as installers gained installation experience with these systems, installation costs fell resulting in lower initial purchase costs. Eventually, these costs began approaching a comparable level to the installation costs for common recessed direct lighting systems. Although most lighting complaints involving computers were resolved or diminished by these systems, these linear indirect lighting systems have proven to be less flexible compared to recessed direct lighting systems.
For example, changes in floor plans are very hard to implement with linear indirect systems. Additional parts or section lengths for linear indirect systems usually must be purchased, and vendors' frequent changes in manufacturing and designs make paint finishes and component part matching very difficult to accomplish. Moreover, structural supports and electrical connections must be relocated inside the building structure when internal walls are erected or moved, which requires additional time and labor. Often, this relocation work is an inconvenience to workers because the relocation must be undertaken while the workspace is in use, which interrupts employees and disrupts the work environment. In recent years, the popularity of these linear indirect lighting systems has decreased as decision-makers recognized the inherent inflexibility of the basic design despite the overall improvement in illumination quality for work areas.
A third lighting system option has evolved featuring recessed indirect lighting. Generally, these systems use a 2-foot by 2-foot ceiling recessed housing installed in a similar fashion as previous direct lighting systems. Lighting is directed upward into the housing and a reflector directs illumination into the space below. Building structure changes (e.g. new or moved walls) are much easier and simpler to implement with these recessed indirect systems compared to linear indirect systems, but visual quality is only slightly improved compared to earlier direct lighting systems. The clear advantage of these newer recessed indirect lighting systems over the earlier systems is increased flexibility. However, screen glare, shadows, mismatched contrast ratios, and high energy consumption remain as undesired attributes of a recessed indirect lighting system because of inflexibilities associated with the current designs. Accordingly, there still remains a need for a superior lighting system featuring improved work area illumination and flexibility of use and increased efficiency in energy consumption.